Textural characteristics and facies of sand‐rich contourite depositional systems

Autor: G. Francés, Emmanuelle Ducassou, Francisco Javier Hernandéz-Molina, Claudia Jones, Marta Pérez-Arlucea, Anxo Mena, Gemma Ercilla, Rachel Brackenridge, Dorrik A. V. Stow, Miguel Ángel Nombela, Estefanía Llave, Irene Alejo
Přispěvatelé: University of London, Ministerio de Economía y Competitividad (España)
Rok vydání: 2018
Předmět:
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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Popis: Brackenridge, Rachel E. ... et al.-- 30 pages, 14 figures, 2 tables
This work presents a detailed study of CONTOURIBER and Integrated Ocean Drilling Program 339 sediment data targeting sand‐rich contourites in the Eastern Gulf of Cadiz. All of the collected sediments are interpreted as contourites (deposited or reworked by bottom currents) on the basis of oceanographic setting, seismic and morphometric features, and facies characteristics. A variety of sandy and associated facies are found across the study area including: (i) bioturbated muddy contourites; (ii) mottled silty contourites; (iii) very fine mottled and fine‐grained bioturbated sandy contourites; (iv) massive and laminated sandy contourites; and (v) coarse sandy/gravel contourites. The thickest sands occur within contourite channels and there is a marked reduction in sand content laterally away from channels. Complementary to the facies descriptions, grain‐size analysis of 675 samples reveals distinctive trends in textural properties linked to depositional processes under the action of bottom currents. The finest muddy contourites (200 μm) are better sorted. They result from the action of dominant bedload transport and winnowing at high current speeds. The results highlight the importance of bottom current velocity, sediment supply and bioturbational mixing in controlling contourite facies. Despite growing interest in their hydrocarbon exploration potential, contourite sands have remained poorly understood. This research therefore has important implications for developing current understanding of these deposits and aiding the correct interpretation of deep marine sands and depositional processes
This research formed part of the lead author's PhD programme at Heriot‐Watt University, supported by an Ali Danesh Scholarship and of the Masters by research from Claudia Jones in the Department of Earth Sciences of the Royal Holloway University of London. The research was also partially supported through the Spanish Ciencia y Tecnologías Marinas projects CTM 2012‐39599‐C03, CGL2016‐80445‐R, and CTM2016‐75129‐C3‐1‐R, and conducted in the framework of ‘The Drifters’ Research Group of the Royal Holloway University of London (RHUL)
Databáze: OpenAIRE
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